Couldn't exactly tell from how you had written it; but you know that (A+B)(A+B)/4 - (A-B)(A-B)/4 is the same as ((A+B)(A+B) - (A-B)(A-B))/4 ... that could save you one division step (haven't seen your code). It's the power of fractions. Okay, later. --Joe ------------------------------------------------------ Get free personalized email at http://four11.iname.com